The present invention relates to a sewing machine with a base consisting of two modules connected detachably to each other and, more specifically, of a central module integral with the column of the sewing machine and a base module containing the parts which cooperate with the needle in order to form the stitch.
As is known, the sewing machines currently available are able to carry out various types of stitches, for example, single or double chain-stitches, knotted stitches, etc. Each of these stitches requires that the parts which cooperate with the needle in arranging the sewing thread or threads should have a special structure. These parts are generally housed in the base of the sewing machine, in the zone where the feed dog teeth for feeding the fabric or similar material during sewing are provided.
Many of the known sewing machines have a substantially monolithic structure and, therefore, in order to produce different types of stitches, it is necessary to have different sewing machines. Other currently known sewing machines, however, have a base with a modular structure. This makes it possible to perform various types of stitches using the same sewing machine, replacing only the part where the feed dog teeth are located.
These modular machines have the advantage that they can be assembled and disassembled as required and that they therefore ensure a high degree of operational flexibility with relatively limited expenditure. However, the machines themselves are in many cases unsatisfactory with regard to their operating efficiency and the accuracy of assembly in the areas where the detachable sections are connected to each other. In fact, it must be remembered that, during operation of a sewing machine, the drive shaft performs a very high number of revolutions and the movements of the various parts are such that minimum tolerances are permissible.
It follows that every incorrectly formed or imperfect joint leads to considerable vibration and overheating and also to inacceptable straining of the parts. In practice, if the joints are not perfect, the advantage which these sewing machines have of being of a sectional nature is substantially offset by operational inefficiency and rapid wear of the assembled parts.
In view of this situation, the general object of the present invention is to devise a sewing machine which has a base consisting of two modules connected detachably to each other and which is able to overcome substantially the abovementioned drawbacks.